<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>DOM演示</title>
</head>
<body>
    <div style="font-size: 30px; text-align: center;" id="tb1">课程表</div>
    <table>
        <tr align="center" class="data">
            <th>学号</th>
            <th>姓名</th>
            <th>分数</th>
            <th>评语</th>
        </tr>
        <tr align="center" class="data">
            <td>001</td>
            <td>张三</td>
            <td>90</td>
            <td>很优秀</td>
        </tr>
        <tr align="center" class="data">
            <td>002</td>
            <td>李四</td>
            <td>92</td>
            <td>优秀</td>
        </tr>
        <tr align="center" class="data">
            <td>003</td>
            <td>王五</td>
            <td>83</td>
            <td>不错，很努力</td>
        </tr>
        <tr align="center" class="data">
            <td>004</td>
            <td>赵六</td>
            <td>98</td>
            <td>666</td>
        </tr>
    </table>
    <br>
    <div style="text-align: center;">
        <input id="b1" type="button" value="改变标题内容" onclick="fn1()">
        <input id="b2" type="button" value="改变标题颜色" onclick="fn2()">
        <input id="b3" type="button" value="删除最后一个" onclick="fn3()">
    </div>
    <script>
        var fn1 = function(){
            document.getElementById('tb1').innerHTML="学员成绩表";
        }
        var fn2 = function(){
            document.getElementById('tb1').style="font-size: 30px;text-align: center; color: red;"
        }
        var fn3 = function(){
            var trs = document.getElementsByClassName('data');
            trs[trs.length-1].remove();
        }
    </script>
</body>
</html>